How do you beat all bruiser teams?

There are a few games i play in which the entire team is tank. When i talk about tanks, thats not a big deal, but when i talk about bruisers, that is. After playing a lot of games against teams that all build tanky and do damage, iv realized that you either completely dominate early and midgame, or lose late game, because then they can pretty much dive your team while dealing heavy damage and tanking the turret and your attacks. Because if bruisers are hard to beat 1 v 1, imagine what 5 of them attacking together are like; very hard to take down, very hard to survive long. Im not saying it is impossible to win against a team like that, but if a 5 team bruiser can give you such an advantage, especially if you or your team loses lane, why isnt this comp used in games much. Do they have any disadvantages i dont know about? What is a good way to counter all bruiser teams? I havent seen exact videos or posts to answer this question, but may i know things like itemization, runes, masteries, in game strategies, etc? Any help would be highly appreciated.